The circulation heater uses baffles to increase the flow rate of the feedstock and decrease the caustic reaction during biodiesel production. Lowering the heater’s watt density reduced the risk of caustic baking and coking to the elements.


Biodiesel production plants produce clean-burning fuel developed from renewable sources such as soybean oil, palm oil, canola oil, chicken renderings, pork tallow and beef tallow, which are generally called feedstock. The chemical name of biodiesel fuel’s chemical is methylester, technically a fatty acid, produced by a chemical process known as transesterification. During this process, methanol, which is the catalyst, and feedstock are combined to produce the biodiesel. A byproduct of the reaction is glycerin.

Although the process to produce biodiesel is relatively straightforward, some of the feedstocks used in commercial biodiesel production facilities exhibit caustic characteristics that, in at least one plant’s case, contributed to process heater failures at an unacceptable rate. And that’s when the plant manager called in Chromalox, a maker of heat and control products headquartered in Pittsburgh.

Chromalox’s solution to the problem involved multiple steps. First, the Chromalox engineering department prepared an analysis report of the failed heater. Second, it evaluated a sample of the feedstock using a controlled test to determine specific reactions occurring at different temperatures. Third, the engineering team offered a prototype circulation heater to the customer to test the proposed engineering changes in a “real world” laboratory - the customer’s own biodiesel production facility.

The prototype heater employed baffles to increase the flow rate of feedstock, which decreased the caustic reaction. A decrease in watt density mitigated the risk of caustic baking and coking to the heater elements, increasing element lifespan and maximizing plant production. (If the process material coked to the heater elements, there would be a drastic reduction in heater life expectancy.) The sheath material was changed from steel to 316 stainless steel to stand up to the caustic feedstock at the operating temperature.

Chromalox’s customer reported an improved total heating system that provided reliable performance despite the severe service. After the successful test period, the custom heater became an engineered standard for the customer’s new facilities. As an added benefit, the enhanced productivity level increased the facility’s uptime.

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